GPU based techniques for deep image merging

Abstract

Deep images store multiple fragments perpixel, each of which includes colour and depth, unlike traditional 2D flat images which store only a single colour value and possibly a depth value. Recently, deep images have found use in an increasing number of applications, including ones using transparency and compositing. A step in compositing deep images requires merging per-pixel fragment lists in depth order; little work has so far been presented on fast approaches.

This paper explores GPU based merging of deep images using different memory layouts for fragment lists: linked lists, linearised arrays, and interleaved arrays. We also report performance improvements using techniques which leverage GPU memory hierarchy by processing blocks of fragment data using fast registers, following similar techniques used to improve performance of transparency rendering. We report results for compositing from two deep images or saving the resulting deep image before compositing, as well as for an iterated pairwise merge of multiple deep images. Our results show a 2 to 6 fold improvement by combining efficient memory layout with fast register based merging.

Keywords

deep image composite GPU performance

Jesse Archer is a Ph.D. student at RMIT University, Melbourne. His research interests are in realtime computer graphics and GPU computing. He completed his bachelor of computer science in 2008, bachelor of IT (games and graphics programming) in 2010, and honours in computer science in 2015 at RMIT University.

Geoff Leach is a lecturer in the School of Science at RMIT University. His major research interests include computer graphics, computational science, and GPU computing. He mostly teaches computer graphics, and has been using OpenGL since version 1.1. He holds a M.App.Sci. degree from RMIT University.

Ron van Schyndel is a senior lecturer from School of Science (formerly School of Computer Science and IT) at RMIT University. He is and has been an active researcher in the domain of digital watermarking for more than 2 decades, and is co-author to some of the most cited papers in the field. He obtained his Ph.D. degree from Monash University on the then nascent topic of digital watermarking, and has obtained many industry grants on watermarking and other applications. His other research interests beyond digital watermarking include signal, image, and vision processing, as well as software infrastructure specifically as applied to mobile navigation for the blind and visually impaired.

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